Update from Monica Bretherton on her Horsebytes column:
http://blog.seattlepi.nwsource.com/horsebytes/archives/139100.asp
I am trying to figure out what her Appy pattern would be called. I think Snowcap, because she has no spots, Marble, because of the pattern in her darker areas, and then she also has non-Appy specific Sabino markings — the high whites and white going over the lip, to complicate it.